1. Field of the Invention
The present invention relates to a light measuring apparatus and to a camera using the light measuring apparatus and, more particularly, to a light measuring apparatus for use in an inexpensive camera in which a film is manually wound by manually rotating a dial (hereinafter referred to as a "low end camera").
2. Background Information
Some conventional low end cameras on the market today do not have a function of detecting brightness. As a result, photographs obtained from such low end cameras often are dark due a low peripheral brightness during a photographing operation.
Other conventional low end cameras have a strobe for emitting light when the peripheral brightness is low during a photographing operation. The structure of this conventional low end camera is such that a charge of the strobe is started by pressing a strobe charging switch separately provided from a release switch. Here, whether or not a flash of the strobe is utilized is left up to the judgment of the photographer. Thus, in the case of the photographer having little experience, there is the possibility that the strobe charging switch is not pressed and the strobe is, therefore, not used even when the peripheral brightness is low, thereby resulting in dark pictures. On the other hand, the strobe may be unnecessarily utilized even when the peripheral brightness is high.
Moreover, conventional low end cameras are required to be operated by a power source having a low voltage and capacity, such as a dry battery (about 1.5 volt), in view of the cost, space and weight constraints associated with such type of cameras.
In conventional cameras which are more expensive than the foregoing conventional low end cameras, a combination of a microcomputer and an analog and digital converter or a comparator is used for judging a brightness. However, the microcomputer requires a power source of at least about 3 volts, and a power source of about 2 volts is required in the case of using a comparator formed of bypolar elements. Furthermore, the microcomputer and the comparator are expensive and are associated with large amounts of current consumption. Thus it becomes impossible to use low capacity power sources, such as a dry battery of about 1 volt, to operate these circuits.
Furthermore, in order to improve the characteristics of the foregoing conventional camera having the brightness judging circuit by preventing changes in temperature and power source voltage, an external memory means, such as an electric erasable programmable read only memory (EEPROM), is used or a temperature compensating circuit is provided. However, such additional structure increases both the cost and the size of the resulting camera.